Slip sensors in gripper means are well known as shown, for example, in U.S. Pat. No. 3,904,234, Hill et al. Hot-wire anemometers for wind velocity measurements are also known wherein a wire is heated by the passage of current therethrough, and wind speed is determined by either current or resistance measurements thereon. Arrays of hot wires are used to determine wind direction. A hot-wire type fluid flow velocity meter is known as shown in U.S. Pat. No. 4,448,070, and a liquid motion sensing device is known as shown in U.S. Pat. No. 4,127,031, which employs a heater for heating water above ambient water temperature. Manipulators which include a thermistor at the jaw face for determining the type of object held by the jaws also are known as shown in an article by R. A. Russell, "Robotics Age," October 1984, pp. 19-22.